Micrometer depth gauge



July 13, 1948. c. E. GEARHART MICROMETER DEPTH GAUGE Filed June 7, 1946 Inventor 7 Carl Edward Gearllart Patented July 13, 1948 UNITED STATES MICROMETER DEPTH 'GAUGE Carl Edward Gearhart, Wilmington, .Del.

Application June '7, 1946, "Serial "N0. fi7'5',002

This invention relates to new and useful improvements and structural refinements in micrometer depth gauges, and the principal object of the invention is to provide a device :of the character-herein described, which is particularly adapted for measuring the depth of screw threads.

A further object of the invention is to provide a micrometer depth gauge which may be readily applied to the work and in which the readin may be easily and directly obtained.

Another object of the invention is to provide a micrometer depth gauge which may be quickly and conveniently adjusted to compensate for wear.

An additional object of the invention is to provide a micrometer depth gauge which is simple in construction and operation, and which cannot easily become damaged.

A still further object of the invention is to provide a micrometer gauge which may be readily disassembled for purposes of cleaning, inspection or repair.

With the above more important objects in view, and such other objects as may become apparent as this specification proceeds, the invention consists essentially of the arrangement and construction of parts as illustrated in the accompanying drawings, in which:

Figure 1 is a cross sectional view of the invention.

Figure 2 is a side elevation thereof.

Figure 3 is a fragmentary side elevation of the gauge frame, and

Figure 4 is a fragmentary detail, illustrating the manner in which the invention is used.

Like characters of reference are used to designate like parts in the specification and throughout the several views.

Referring now to the accompanying drawings in detail, the invention embodies in its construction a frame designated generally by the reference character 5, the same consisting of a block 6 and a barrel '1. The block 6 is configurated substantially as shown and is formed on one side thereof with a. substantially flat gauging surface 8, its relatively opposite surface being upraised as at 9, to carry the aforementioned barrel.

The barrel 1 is provided with an externally threaded portion Iii, this being adapted to receive an internally threaded thimble H. The internal threading of the thimble is illustrated at [2, and the body of the thimble is provided medially of its length with a knurled shoulder IS.

The thimble l l is also formed with an externally 1 Claim. (01. ss-110) threaded portion It, and an externally knurled,

internally threaded cap I5 is positioned 'on the' threaded portion M aswillbe clearly apparent fromthe accompanying drawing.

The bore It oftherbarrel 'l is extended through the block 6 and a spindle I'Lis slidably'androtatably positioned in saidlbore, with one-rend; of

the spindle projecting "from the gauging surface 8. The projecting end portion of the spindle l1 assumes a substantially frusto-conical configuration as at E8, the purpose thereof being hereinafter more fully explained.

The remaining end of the spindle I1 is formed integrally with a screw threaded shank i9, and a pair of lock nuts are positioned on this shank, as is best shown in Figure 1. It will be noted that the nuts 21] are clamped between the inner end surface 2| of the cap l5 and the adjacent end surface 22 of the thimble ll. If desired, the end 22 of the thimble may be counterbored to receive the nuts 20, substantially as shown in the drawing. Furthermore, the end surface 2| of the cap i5 is formed with a blind bore or recess 23, this being adapted to freely receive the end portion of the shank l9.

Suitable graduations 24 are provided on the thimble ii, and coacting graduations 25 are inscribed on the lateral surface of the barrel 1.

When the invention is placed in use, such as for example, in measuring the depth of thread on a bolt, the gauge is applied so that the gauging surface 8 lies upon the outside diameter of the screw thread to be measured.

Thereupon, the thimble H and the associated cap l5 are rotated, this rotation being simultaneous with the rotation of the spindle H, whereby the projecting end portion I8 of the spindle engages the threads 26 of the screw 21, as is shown in Figure 4. It will be apparent that in this manner, the length of the spindle H which projects from the gauging surface 8 will correspond to the depth of the threads 26, and the appropriate measurement made be directly read on the graduated scales 24, 25. Inasmuch as it is preferable that the spindle portion [0 contacts the sides of the thread rather than the root thereof, the minor diameter of the frusto-conical portion !8 may be somewhat larger than the distance 28 at the root of the threads. In this manner, a certain amount of space will exist between the end of the portion 18 and the root of the threads, and the graduations 24, 25 should, of course, be calibrated so as to compensate for this spacing.

The gauge may be easily adjusted to compensate for wear of the portion I8, this being accomplished by simply removing the cap l5 from the thimble H and adjusting the setting of the nuts 20 on the shank 19.

It should be understood that gauges constructed in accordance with this invention may possess spindles of different diameters and the portion l8 of such spindles may be configurated in accordance with the size, form and finesse of the thread for which they are intended.

It is believed that the advantages and use of the invention will be clearly understood from the foregoing disclosure and accordingly, further description thereof at this point is deemed unnecessary.

While in the foregoing there has been shown an externally threaded portion on said barrel, an internally threaded thimble positioned on said externally threaded portion, an externally threaded portion on said thimble, an internally threaded cap positioned on the externally threaded portion of said thimble, a spindle slidably and rotatably positioned in said bore with one end thereof projecting from said gauging surface, a screw threaded shank at the remaining end of said spindle, a pair of lock nuts on said shank, said nuts being clamped between said thimble andsaid cap, and coacting graduations on said and described the preferred embodiment of this thimble and on said barrel, said graduations being. readable in accordance with the length of the projecting portion of said spindle.

CARL EDWARD GEARI-IART.

REFERENCES CITED The following references are of record in the file of this patent: 1

UNITED STA'IES PATENTS Number Name Date 438,851 Malmquist Oct. 21, 1890 623,748 Walters April 25,1899 1,656,302 Swaney Jan. 17, 1928 1,817,622 Hansen Aug. 4, 1931 

